Fatal error: Uncaught Error: Call to a member function query() on null in /www/wwwroot/library/DbPdoMysql.class.php:137
Stack trace:
#0 /www/wwwroot/library/DbPdoMysql.class.php(261): DbPdoMysql->querySql('SELECT * FROM t...')
#1 /www/wwwroot/baixian/bx_mobile/models/AnswerModel.class.php(187): DbPdoMysql->getMoreSelect('tb_bill', '*', 'WHERE Fid>0')
#2 /www/wwwroot/baixian/bx_mobile/controllers/BaseController.php(327): AnswerModel->getAdsList('WHERE Fid>0')
#3 /www/wwwroot/baixian/bx_mobile/controllers/CoursesController.php(24): BaseController::setUiPath()
#4 /www/wwwroot/baixian/bx_mobile/controllers/Courses/Categorys.class.php(24): CoursesController->_run()
#5 /www/wwwroot/baixian/bx_mobile/start/index.php(14): Categorys->__construct()
#6 {main}
thrown in /www/wwwroot/library/DbPdoMysql.class.php on line 137